The present invention relates to a stereoscopic endoscope which allows an observer to view a three-dimensional image of an object under test.
A stereoscopic endoscope is used to observe an object or cavity internal to a machine or the human body. Examples of rigid type stereoscopic endoscopes are disclosed in for example, U.S. Pat. No. 4,364,629 and Japanese Laid Open Publication Hei. 6-194581. In these examples, the stereoscopic endoscopes have an insertion portion which includes an objective lens for forming an image of the object and a relay lens for transmitting the light to an exit pupil of the insertion portion. The stereoscopic endoscopes also include an observing portion, which includes an optical device for splitting the light at the exit pupil and directing the split light beams to a left and right optical imaging system, through which an observer would view a three-dimensional image of the object.
However, if the optical device for splitting the light beam is not positioned correctly, the three-dimensional effect of the image may be reduced, thereby reducing the effectiveness of the endoscope. Further, even if the optical device for splitting the light beam is positioned correctly for an object located near to the insertion portion of the endoscope, the three-dimensional effect of an image of an object located far away from the insertion point of the endoscope may be reduced. This also reduces the effectiveness of the endoscope.
In conventional stereoscopic endoscopes, the three-dimensional image is viewed directly, using eyepiece lenses, or indirectly using an imaging device such as a CCD, and a video processor. Use of an imaging device allows the images to be viewed by many people, through the use of a monitor and special viewing glasses. However, this requires extra hardware and elaborate image processing. In a direct viewing endoscope, the image may be viewed easily and quickly through the eyepiece lenses, but by only one person at a time. Thus, extra time will be required if many people are to view the image.
Further, in a conventional stereoscopic endoscope that employs the imaging devices, one imaging device is used with each optical system, thereby increasing the cost of manufacturing the cost of the endosocope.
In conventional stereoscopic endoscopes the optical device for splitting the light beam uses a series of reflective surfaces in order to properly split the light beam. Therefore, the positional relationship between the various reflective surfaces must be set precisely. Further, in order properly position all of the reflective surfaces, the size of the endoscope must be made large, thereby reducing the effectiveness of the endoscope. Furthermore, the number of parts required to manufacture the endoscope is increased.
In a conventional stereoscopic endoscope, light is provided to illuminate the object by using a separate light source and an optical guide. The optical guide is housed in the insertion portion of the stereoscopic endoscope, and is parallel to the optical axis of optical system used for viewing the image. This results in the diameter of the insertion portion being large, and therefore the insertion portion cannot be as easily inserted into the cavity.
It is therefore an object of the present invention to provide an improved stereoscopic endoscope in which the position of a device for splitting the light beam, can be positioned at the standard correct position quickly and accurately.
It is another object of the present invention to provide an improved stereoscopic endoscope in which the three-dimensional effect of the image viewed using the endosocope can be changed quickly and easily.
It is a further object of the present invention to improve the utility of a stereoscopic endoscope in which the image of the object can be viewed by many people or by a single person, quickly.
It is yet a further object of the present invention to provide an improved stereoscopic endoscope in which a single imaging device is used, thereby reducing the size of the endoscope and the number of parts required to manufacture the endosocope.
It is still another object of the present invention to provide an adapter for use with a stereoscopic endoscope which allows a wide range of insertion portions of monocular endoscopes to be used with an observing portion of the stereoscopic endoscope.
It is still a further object of the present invention to provide an improved stereoscopic endoscope which can illuminate the object to be viewed without increasing the diameter of the insertion portion of the stereoscopic endoscope.
According to a first aspect of the present invention, there is provided a stereoscopic endoscope which includes: a primary optical system for transmitting light, reflected by an object located near a first end of the primary optical system; to a second end of the primary optical system, a device for dividing the light transmitted to the second end of the primary optical system into two light beams; and a pair of secondary optical systems. Each of the secondary optical systems has an imaging device which outputs an image signal. Each of the secondary optical systems receives one of the light beams and forms an image of the object on its corresponding imaging device. The stereoscopic endoscope also includes a device for adjusting a position of the light dividing device relative to an optical axis and exit pupil of the primary optical system, and a device for detecting a position of the light dividing device in accordance with each of the output image signals.
In a preferred embodiment, the detecting device detects the position of the light dividing device in accordance with a distribution of a brightness of each image formed on each of the imaging devices, by an object having a uniform brightness. Further, the stereoscopic endoscope calculates an amount and direction of movement required to move the adjusting device to a standard correct position, in accordance with the distribution of brightness of the images formed on each of the imaging devices. Therefore, the stereoscopic endoscope can automatically position the light dividing device at the standard correct position, quickly and accurately. This ensures that an image having the proper three-dimensional effect can be observed by the user.
Still preferably, the stereoscopic endoscope also includes a device for processing the image signals to produce left and right images, and a device for calculating the amount and direction of movement required to position the light dividing device at the standard correct position.
In a preferred embodiment, the processing device and the calculating device are located in a common, which is separate from the housing of the stereoscopic endoscope.
In another preferred embodiment, the processing device and the calculating device are located in separate housings. Therefore, during normal use of the stereoscopic endoscope, only the processing device needs to be attached to the stereoscopic endoscope, thereby reducing the size of the stereoscopic endoscope system.
In yet another preferred embodiment, the calculating device is provided inside the stereoscopic endoscope housing, and the processing means is provided in a separate housing. This reduces the overall size required for the stereoscopic endoscope system.
Optionally, the primary optical system is provided by a monocular endoscope, which is attached to an adapter. The adapter is then attached to an observing portion of the stereoscopic endoscope which includes the light dividing device and the pair of secondary optical systems. This permits automatic positioning of the light dividing device relative to an exit pupil of any monocular endoscope.
The position of the adapter relative to the light dividing device may be adjusted by varying a position of adjustment screws used to secure the adapter to the observing portion. Furthermore, by including motors, the adjustment of the position of the screws can be done automatically.
In another preferred embodiment, the stereoscopic endoscope includes an indicator for indicating the calculated amount and direction of movement required to position the light dividing device at the standard correct position. The adjustment of the position of the light dividing device can then be done manually using the indicated information.
In yet another preferred embodiment, a single imaging device replaces the imaging device used in each of the secondary systems. This reduces the overall cost of manufacturing the stereoscopic endoscope.
In order to further reduce the cost of manufacture, the size of the imaging device can be reduced, and the formation of the images by the two secondary optical systems on the imaging device are alternated.
The viewing of the three-dimensional image of the object may be achieved by using a monitor to alternately display the left and right images, and special glasses to alternately transmit the left and right images to the corresponding eye of the observer.
In a preferred embodiment, the light dividing device is a mirror block having two reflective surfaces which are perpendicular to each other, and arranged at a 45xc2x0 angle to an optical axis of the primary optical system. Further, the adjusting device may include:
a frame for holding the mirror block;
a first screw fitted into the holding frame;
a first gear which meshes with the first screw, the first gear rotating about an axis;
a second screw fitted into a mounting member attached to the observing portion and having a nut through which the first screw is threaded; and
a second gear which meshes with the second screw, the first gear rotating about another axis.
The holding frame is moved in a first plane in response to a rotation of the first gear, and is moved in a second plane in response to a rotation of the second gear, with the first plane being perpendicular to the second plane.
In an alternative embodiment, the mirror block is replaced with a pair of mirrors attached to separate supports. The pair of mirrors are arranged in a similar position relative to the primary optical axis, as the reflective surfaces of the mirror block. This reduces the need for a mirror block and results in reduction in the weight of the stereoscopic endoscope.
According to a second aspect of the present invention, there is provided a stereoscopic endoscope having an optical system for transmitting a luminous flux, reflected by an object located near a first end of the optical system, to a second of the optical system. The stereoscopic endoscope forms a first image of the object in accordance with a first area of the luminous flux, and forms a second image of the object in accordance with a second area of the luminous flux. The second area of the luminous flux does not overlap the first area of the luminous flux. The stereoscopic endoscope also includes a device for adjusting a distance between an optical axis of the first area of the luminous flux and an optical axis of the second area of the luminous flux, such that a size of the first area of the luminous flux remains equal to a size of the second area of the luminous flux.
In a preferred embodiment, the stereoscopic endoscope includes a device for guiding the first area of the luminous flux to a first device for forming a first image, and a device for guiding the second area of the luminous flux to a second device for forming the second image.
Preferably, the adjusting device includes a screw and a gear which rotates about an axis and meshes with a center of the screw. The two guiding devices are attached to separate supports, with one support threaded onto the screw on one side of the center of the screw, and the other support threaded onto the screw on the other side of the center of the screw. By rotating the gear, the supports move towards or away from each other along an axis of the screw.
Therefore, the distance between the central axis of the two portions of the luminous flux which form the first and second images, can be adjusted. Thus, the three-dimensional effect of the observed image can be adjusted, by rotating the gear.
In a preferred embodiment the guiding devices are mirrored surfaces for reflecting the first area of the luminous flux to the first image forming device, and for reflecting the second area of the luminous flux to the second image forming device.
In another preferred embodiment, each of the first and second image forming devices includes an imaging lens for forming the respective image and an eyepiece lens for viewing the image.
In yet another preferred embodiment, each of the first and second image forming devices includes an imaging lens for forming the respective image and an imaging device for detecting the image and for outputting an image signal. The imaging device can include a CCD. Optionally, each of the secondary optical systems may also have an eyepiece lens to allow simultaneous direct viewing of the image, and indirect viewing using the imaging devices.
Further optionally, the primary optical system is provided by an insertion portion of a monocular endoscope which is attached using an adapter to an observing portion of the stereoscopic endoscope. Therefore, the range of endoscopes which may be used with the apparatus having the present invention is increased.
Alternatively, each guiding device and corresponding image forming device is replaced with a separator lens and an imaging device. Each separator lens receives one of the respective portions of the luminous flux and forms an image, which is detected by the corresponding imaging device. The imaging devices output image signals, which can be processed to produce a three-dimensional image. Therefore, in this case, the adjusting device changes the distance between the optical axes of the separator lenses.
Optionally, an optical fiber bundle may be used to transfer the luminous flux from the separator lens to the corresponding imaging device. This increases the flexibility of positioning the imaging devices.
Alternatively, the imaging device is replaced with an imaging lens and an eyepiece lens for direct viewing of the three-dimensional image by an observer.
In another alternative embodiment, the stereoscopic endoscope has a single imaging device and each of separator lenses forms one of the images on the single imaging device. By employing one imaging device, the cost of manufacturing the stereoscopic endoscope can be decreased.
According to a third aspect of the present invention, there is provided a stereoscopic endoscope which includes a primary optical system for transmitting light, reflected by an object located near a first end of the primary optical system, to a second end of the primary optical system, a plurality of secondary optical systems, each of the secondary optical systems receiving a separate portion of the light and forming an image of the object; and a plurality of devices for guiding a separate portion of the light transmitted to the second end of the primary optical system, to each of the secondary optical systems. The stereoscopic endoscope also includes a device for selecting a predetermined number of the images for viewing the object. Therefore, by selecting images which are formed by secondary optical systems which are closer together or further apart, the three-dimensional effect of the observed image can be varied.
In a preferred embodiment, each of the plurality of guiding devices and corresponding plurality of secondary optical systems is replaced with a separator lens, and an imaging device. Each separator receives one of the portions of transmitted light and forms an image of the object on the corresponding imaging device. The imaging devices output image signals corresponding to the images formed by the separator lenses.
In another preferred embodiment, each of the guiding devices includes a separator lens for receiving the separate portions of the light. Further, each of the secondary optical systems includes an imaging lens, an imaging device, and an optical fiber bundle for guiding the received portions of the light from the separator lens to the imaging lens. The imaging lens forms an image on the imaging device, which outputs the image signal.
Alternatively, some of the imaging devices are replaced with eyepiece lenses to allow direct viewing of the three-dimensional image of the object. Therefore, simultaneous direct viewing using the eyepiece lenses and indirect viewing using the imaging devices is possible.
Optionally, some of the secondary optical systems are provided with an eyepiece lens, a half mirror and an imaging device. This also allows direct viewing with the eyepiece lens as well as more choices for indirectly viewing the image using the imaging devices.
Preferably, at least three secondary optical systems, and three guiding devices are provided.
In another preferred embodiment, one imaging device is provided and two secondary optical systems are provided to form two images on two areas of the single imaging device.
Optionally, each of the secondary optical systems is provided with a liquid crystal shutter, which allows or prohibits the formation of the image by the secondary optical system. Therefore, when the image is being formed by one of the secondary optical systems on the single imaging device, the liquid crystal shutter of the other secondary optical system prohibits the formation of the other image by the other secondary optical system.
In this case, the first area and second area of the single imaging device can overlap, and therefore, the size of the single imaging device can be reduced, thereby reducing the manufacturing cost of the stereoscopic endoscope.
According to a fourth aspect of the present invention, there is provided a stereoscopic endoscope which includes a primary optical system for transmitting light, reflected by an object located near a first end of the primary optical system, to a second end of the primary optical system; a prism for dividing the light transmitted to the second end of the primary optical system into two light beams, with the two light beams not being parallel to each other; and a pair of secondary optical systems which receive one of the light beams and forming an image of the object. Therefore, the size of the stereoscopic endoscope can be reduced since extra space is not required to have parallel secondary optical systems.
In a preferred embodiment, the primary optical system is housed within an insertion portion of the stereoscopic endoscope, and the secondary optical systems are housed within an observing portion of the endoscope. The insertion portion is attached to the observing portion using a cylindrical adapter. This allows the insertion portion of monocular endoscopes to be used with the observing portion of the stereoscopic endoscope.
In another preferred embodiment, each of the secondary optical systems includes an imaging lens for forming an image of the object in accordance with the refracted light beam, and an imaging device for detecting the images formed by the imaging lens, with the imaging devices outputting image signals.
Alternatively, the stereoscopic endoscope is provided with a single imaging device. The images formed by the imaging lenses of the secondary optical systems is formed on different areas of the single imaging device.
Optionally, each of the secondary optical systems is provided with a liquid crystal shutter, which allows or prohibits the formation of the image by the secondary optical system. Therefore, when the image is being formed by one of the secondary optical systems on the single imaging device, the liquid crystal shutter of the other secondary optical system prohibits the formation of the other image by the other secondary optical system.
In this case, the first area and second area of the single imaging device can overlap, and therefore, the size of the single imaging device can be reduced, thereby reducing the cost of manufacturing the stereoscopic endoscope.
In yet another preferred embodiment, each of the secondary optical systems includes a prism for refracting the received light beams, such that the refracted light beams are parallel to an optical axis of the primary optical system, an imaging lens for forming an image of the object in accordance with the refracted light beam, and an eyepiece lens for viewing the image formed by the imaging lens. This permits direct viewing of the three-dimensional image.
Alternatively, a single deflecting prism is provided for refracting the received light beams. This reduces the number of parts required to manufacture the stereoscopic endoscope.
Further, a single roof prism may replace the prism used for dividing the light. This results in a less complex prism being used in the manufacturing of the stereoscopic endoscope.
According to a fifth aspect of the present invention, there is provided a method of adjusting a position of a light dividing mechanism of a stereoscopic endoscope to a predetermined position. Light from an object having a uniform brightness is transmitted by a primary optical system of the stereoscopic endoscope to the light dividing mechanism, which divides the light into two light beams, with each light beam being incident on an imaging device. The method includes the steps of:
detecting a brightness pattern of an image formed on each of the imaging devices;
determining a direction and amount of movement required to position the light dividing mechanism at the predetermined position, in response to the detected brightness pattern of each of the images; and
adjusting the position of the light dividing mechanism in accordance with the direction and movement amount determined in the determining step.
In a preferred embodiment, the determining step includes the steps of calculating a direction of movement of the light dividing mechanism, and comparing a position of the light dividing mechanism with the predetermined position. Further, the adjusting step includes the step of driving the light dividing mechanism by a fixed amount. Furthermore, the detecting step, the determining step and the adjusting step are repeated until the determining step determines that the position of the light dividing mechanism is at the predetermined position. Since the calculating step only determines a direction of movement, the number of bits required for the calculation is low.
Alternatively, the calculating step also calculates the amount of movement required to move the light dividing mechanism to the predetermined position. In this case, the driving step drives the light dividing mechanism directly to the predetermined position, after the first calculation. Therefore, the light dividing mechanism can be quickly and accurately placed at the predetermined position.
According to a sixth aspect of the present invention, there is provided an adapter for enabling a monocular endoscope to be used with a stereoscopic observing portion. The observing portion includes a device for dividing light transmitted by the monocular endoscope, into two light beams, by a pair of optical systems. Each of the optical systems receives one of the light beams and forms an image of the object. The adapter includes a device for connecting the observing portion of the stereoscopic endoscope to the monocular endoscope.
Thus, the range of insertion portions that can be used with the observing portion of the stereoscopic endoscope is increased.
In a preferred embodiment, the connecting device includes a plurality of screws and nuts for attaching the adapter to the observing portion. Therefore, the adapter can be easily attached to the observing portion of the stereoscopic endoscope.
In another preferred embodiment, the connecting device includes a device for adjusting a positional relationship of the observing portion and the monocular endoscope. This allows for accurate positioning of the monocular endoscope in relation to the light dividing device of the observing portion. Therefore, the three-dimensional effect of the image can be changed by using the adjusting device.
In the preferred embodiment, the adjusting device includes a first set of screws oriented along a first direction, and a second set of screws oriented along a second direction. The second direction may be perpendicular to the first direction. Further, the first set of screws adjusts a position of the adapter relative to the observing portion along the first direction. The second set of screws adjusts a position of the adapter relative to the observing portion along the second direction. Therefore, accurate two dimensional adjustment of the position of the monocular endoscope relative to the observing portion can be achieved.
Optionally, each screw is rotated by a motor. This allows automatic adjustment of the position of the monocular endoscope relative to the observing portion.
According to a seventh aspect of the present invention, there is provided a stereoscopic endoscope which has a primary optical system for transmitting light, reflected by an object located near a first end of the primary optical system, along a first optical path to an exit pupil located at a second end of the primary optical system. The stereoscopic endoscope is also provided with a device for dividing the light transmitted to the second end of the primary optical system into two light beams, and a pair of secondary optical systems. Each of the secondary optical systems receives one of the light beams and forms an image of the object. The stereoscopic endoscope further provides a device for emitting light through a second optical path of the primary optical system which is parallel to the first optical path. The emitted light is incident on the object and does not interfere with the first optical path. Therefore, the stereoscopic endoscope provides the light required for viewing the object, and an auxiliary light source is not need.
According to an eighth aspect of the present invention, there is provided a stereoscopic endoscope having a primary optical system for transmitting light, reflected by an object located near a first end of the primary optical system, to a second end of the primary optical system. The stereoscopic endoscope also includes a device for dividing the light transmitted through the primary optical system into two light beams, and a pair of secondary optical systems. Each of the secondary optical systems receives one of the light beams and forms an image of the object. Further, each of the secondary optical systems includes an eyepiece lens for viewing the image and an imaging device for detecting the images formed by the secondary optical system. A half mirror is provided in each secondary optical system for reflecting half of the received light to one of the eyepiece lens and the imaging device, and for transmitting the other half of the received light to other of the eyepiece lens and the imaging device.
Therefore, the three-dimensional image can be viewed directly using the eyepiece lenses or indirectly using the imaging devices. This increases the facility of the viewing of the three-dimensional image observed using the stereoscopic endoscope.
In a preferred embodiment, the light dividing device includes two mirrors arranged perpendicular to each other, with each of the mirrors arranged at a 45xc2x0 angle to an optical axis of the primary optical system. Further, stereoscopic endoscope also includes a device for adjusting a distance between each of the two mirrors. Therefore, by adjusting the distance between the two mirrors, the three-dimensional effect of the image can be changed.
In another preferred embodiment, the dividing device includes a half mirror for dividing the light into the two light beams. This reduces the number of parts required to manufacture the endoscope.
According to a ninth aspect of the present invention, there is provided a stereoscopic endoscope having a primary optical system for transmitting a luminous flux, reflected by an object located near a first end of the optical system, to a second end of the optical system. The stereoscopic endoscope also includes a device for forming a first image of the object in accordance with a first area of the luminous flux, and another device for forming a second image of the object in accordance with a second area of the luminous flux. The second area of the luminous flux does not overlap the first area of the luminous flux. A single imaging device detects the first image and the second image and outputs an image signal. By using only one imaging device, the cost of manufacturing the stereoscopic endoscope can be decreased.
In a preferred embodiment, the first image is formed on a first portion of the imaging device, and the second image is formed on a second portion of the imaging device, which is separate from the first portion. Therefore, by processing the image signal, the left and right images can be obtained.
In another preferred embodiment, each image forming device is provided with a liquid crystal shutter, which controls a timing of the image formation by alternately prohibiting and allowing transmission of light through the image forming device. Further, the first and second images are alternately formed on overlapping portions of the imaging device. Therefore, the size of the imaging device can be reduced, and the cost of manufacturing the stereoscopic endoscope can also be reduced.